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The temperature governed global partitioning of semi-volatile air pollutants leads to a gradual accumulation of these compounds in the air of high latitudes. Because high quantities of the persistent organic pollutants (POPs) are scavenged from the atmosphere by plant leaves, the vegetation in sub-arctic regions and the cooler mountain ecosystems is an important receptor of airborne xenobiotics. After...

Shrubs of the Great Basin desert in Utah are subjected to a prolonged summer drought. One potential consequence of drought is a reduced water transport capability of the xylem. This is due to drought-induced cavitation. We used the centrifuge method to measure the vulnerability of root and stem xylem to cavitation in six native shrub species. The shrubs fall into three categories with regards to rooting...

The reduction of agricultural use of alpine ecosystems went hand in hand with an increase of soil erosion in many areas. A possible reason for this phenomenon is the more frequent snow gliding in winter. In a large research program (part of the ECOMONT project) managed areas, as well as areas that are not used or only used to some extent, were investigated in order to find out their liability to snow...

Gall makers can be considered microhabitat engineers, because their galls provide both a food resource and a habitat that can be exploited by herbivorous and omnivorous organisms that do not feed on the galling insect. We compiled literature data on inquilines of insect-induced galls for 112 galler systems in order to examine physiological, ecological and taxonomic patterns of diversity. We measured...

Organisms may spread as travelling waves proceeding with a constant velocity, or as dispersive waves with a continuously increasing velocity. Whereas theory predicts existence of dispersive waves, experimental proof is virtually absent from literature. One major problem is to distinguish between the increasing velocity of a travelling wave during the build-up phase and the continuously increasing...

In savannas, degrading trends such as increasing woody cover are caused by livestock ranging. Hence, identifying sustainable utilisation intensities is crucial for range management. However, knowledge concerning herbivory effects on herbaceous vegetation and primary productivity, but also productivity of and foraging on woody vegetation (browsing) is incomplete. Consequences of these knowledge gaps...

We investigated the occurrence of herkogamy and dichogamy in 43 populations of the grassland biennial Gentianella campestris in Sweden, and experimentally tested their significance for the reproductive system of the species. Furthermore, we performed a heritability test to evaluate the potential for selection on traits related to herkogamy. Dichogamy did not occur in the studied populations, and herkogamy...

The nymphalid butterfly Erebia medusa is a typical species of meadows that are poor in nitrogen and fallow land. In forests, it is only found on clearings with meadow-like structures. However, it is missing on wind exposed places, too. 239 imagoes of E. medusa were sampled in the Aggtelek Karst region (north-eastern Hungary) at six different localities at the end of May 1997. The sample sizes varied...

Phenotypic and genetic variation of the rare plant species Arnica montana L. were investigated in populations which had been fragmented by afforestation since 1930 in the Rhön, a mountain region in Central Germany. The aim of the study was to analyse whether small populations show less genetic variation and a lower fitness than large populations. Morphological and reproductive traits from eleven Arnica-populations...

We studied correlations between geographical range sizes and plant structural and ecological characteristics of 45 palm taxa occurring in western Amazonian lowland rainforests. The studied plant features were stem height, fruit size, cespitose growth form, response to variation in soil cation content and occurrence in seven different not soil-related habitat types. The most widespread palms tended...

Foliage of transgenic maize Zea mays L., expressing a Cry1Ab protein derived from Bacillus thuringiensis (Berliner) subsp. kurstaki, was compared with foliage of the corresponding non-transgenic maize variety in laboratory feeding and decomposition experiments to study the effects of the B. thuringiensis protein on the chemical composition of the maize leaves, on the decomposer Porcellio scaber (Crustacea:...

In a column irrigation experiment the effects of different amounts of honeydew on the dynamics of soil respiration, dissolved organic carbon and nitrogen (DOC and DON, respectively) and inorganic nitrogen species in the organic layer of a forest soil were investigated. On the base of hourly and daily sampling, the application of different field-relevant amounts of honeydew-DOC caused short-time effects...

Embedded in species-poor grasslands, fairy circles are circular or sub-circular patches devoid of any vegetation. Characteristically, the circumference of each circle shows a band of more densely packed taller tussocks within a shorter, more sparse grassland matrix. The average diameter of the circles is between 58 m. Restricted to sites showing deep sandy deposits, in Namibia, fairy circles occur...

Eddy covariance (EC) measurements of CO 2 are widely used to assess the CO 2 budget of ecosystems. However, important uncertainties exist about how to obtain flux values that are representative for the regional scale from local-scale EC measurements. This paper addresses the issues of nocturnal CO 2 advection in non-flat topography, and the representativeness of the local clover-rich...

The most extreme adaptations to seasonal food scarcity and low ambient temperatures are daily torpor and hibernation. Torpor is realized in the small malagasy cheirogaleids, Microcebus and Cheirogaleus. In the present overview, I reviewed information on daily and prolonged torpor of the gray mouse lemur (Microcebus murinus). Specifically, I related the occurrence of seasonal changes in body mass,...

The re-colonization of grassland by Silaum silaus was analysed on fields in the Saale River floodplain changed to extensive management in 1989 (restoration grassland). The species was still very rare in 1999 and did not reappear at all in areas distant from seed sources. Soil nutrient content and seedling mortality were studied and compared with adjacent permanently extensive grassland where Silaum...

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